Signal-to-noise ratio enhancing touch sensing apparatus using charge sharing method

ABSTRACT

A touch sensing apparatus is disclosed. The touch sensing apparatus includes a logic control module, at least one storage control module, and at least one decoding control module. The logic control module is used to generate a plurality of control signals having different control timings. The plurality of control signals includes a storage control signal and a decoding control signal. Each storage control module includes a plurality of storage capacitors, and respectively stores each of sensed voltages in different storage capacitors at different times according to a storage control timing of the storage control signal. The sensed voltages are analog data sensed from scan lines of an ITO sensor. The decoding control module is used to decode the sensed voltages stored in the storage capacitors according to a decoding control timing of the decoding control signal to output the decoded analog data.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to touch sensing, in particular, to a touchsensing apparatus using the charge sharing concept to realize thefunction of analog filter, so that the interference to touch sensingcaused by the noise generated by the liquid crystal panel and externalenvironment will be reduced.

2. Description of the Prior Art

With the rapid progress of technology, the conventional display has beenreplaced by TFT-LCD gradually, and the TFT-LCD is widely used in variouselectronic products such as television, flat display, mobile, tablet PC,and projector. As to the TFT-LCD with touch control function, touchsensor is one of the important modules of the TFT-LCD, and theperformance of the touch sensor will also directly affect the entireeffectiveness of the TFT-LCD.

In general, the conventional LCD with mutual inductance capacitor touchfunction includes a display panel, an ITO sensor, and a touch controlchip. Wherein, the ITO sensor includes a plurality of sensing lines anddriving lines, and the touch control chip includes a plurality of pins.The sensing lines are coupled to the pins respectively. After thedriving line transmits a driving pulse and couples a small voltage atthe sensing line, the touch control chip will sense the coupled voltageand judge whether the ITO sensor is touched according to the coupledvoltage.

However, the above-mentioned conventional LCD touch sensing method hasserious drawbacks, such as the scanning rate is too low, the operationof the touch control chip is seriously affected by the noise generatedby the display panel, even the touch point is misjudged. In order toavoid the noise generated by the panel, a layer of insulating materialis disposed between the ITO sensor and the panel; however, this methodwill increase the cost, and the thickness of the entire apparatus willbe increased, it is unfavorable to the design of mechanism.

Therefore, the invention provides a touch sensing apparatus using thecharge sharing concept to realize the function of analog filter to solvethe above-mentioned problems.

SUMMARY OF THE INVENTION

A scope of the invention is to provide a touch sensing apparatus. In anembodiment of the invention, the touch sensing apparatus includes alogic control module, at least one storage control module, and at leastone decoding control module. The logic control module is used forgenerating a plurality of control signals having different controltimings, and the plurality of control signals includes a storage controlsignal and a decoding control signal. Each storage control moduleincludes a plurality of storage capacitors and respectively stores eachof sensed voltages in different storage capacitors at different timesaccording to a storage control timing of the storage control signal,wherein the sensed voltages are analog data sensed from scan lines of anITO sensor. The at least one decoding control module is used fordecoding the sensed voltages stored in the storage capacitors accordingto a decoding control timing of the decoding control signal to outputthe decoded analog data.

In practical applications, each decoding control module can respectivelydecode the sensed voltages stored in different storage capacitors atdifferent times, or perform an analog filtering process to and decodethe sensed voltages stored in different storage capacitors at the sametime. After the at least one decoding control module decodes all of thesensed voltages stored in the storage capacitors and transmits thedecoded voltages to the logic control module, the storage control modulewill perform a discharge process to the storage capacitors.

Compared to the prior arts, the touch sensing apparatus of the inventionuses the charge sharing concept to realize the function of analogfilter, not only the interference to touch sensing caused by the noisegenerated by the liquid crystal panel and external environment can beeffectively reduced, but also the reporting rate of the entire systemwill be not reduced and the power consumption will be increased,therefore, the touch sensing apparatus can sense the touch points on thetouch panel more accurately to largely reduce the probability ofmisjudgment.

The advantage and spirit of the invention may be understood by thefollowing detailed descriptions together with the appended drawings.

BRIEF DESCRIPTION OF THE APPENDED DRAWINGS

FIG. 1 illustrates a schematic figure of the touch sensing apparatussensing the touch points on the ITO sensor in the invention.

FIG. 2 illustrates a circuit schematic figure of an embodiment of thestorage control module and the decoding control module of the touchsensing apparatus.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the invention is a touch sensing apparatus. Inthis embodiment, the touch sensing apparatus can be a mutual inductancecapacitor touch sensing apparatus capable of sensing a plurality of datafrom an ITO sensor at the same time and avoiding the misjudgment oftouch points caused by the sensed data affected by the noise of the LCDpanel.

Please refer to FIG. 1. FIG. 1 illustrates a schematic figure of thetouch sensing apparatus sensing the touch points on an ITO sensor in theinvention. As shown in FIG. 1, the liquid crystal display includes anITO sensor 100 and a touch sensing apparatus 1. In general, the LCDpanel is attached under the ITO sensor 100, but not limited to this. Thetouch sensing apparatus 1 includes a logic control module 10, aplurality of pins 20, at least one driving/sensing module 30, at leastone storage control module 40, at least one decoding control module 50,an amplifying module 60, and an analog/digital converting module 70.

Wherein, the driving/sensing module 30, the storage control module 40,the decoding control module 50, the amplifying module 60, and theanalog/digital converting module 70 are all modules for processinganalog signals, and the logic control module 10 is a module forprocessing digital signals. The driving/sensing module 30 is coupled tothe logic control module 10 and the plurality of pins 20; the storagecontrol module 40 is coupled to the logic control module 10 and thedriving/sensing module 30; the decoding control module 50 is coupled tothe logic control module 10 and the storage control module 40; theanalog/digital converting module 70 is coupled to the amplifying module60 and the logic control module 10.

In this embodiment, the logic control module 10 is used for generating aplurality of control signals having different control timings. Forexample, the logic control module 10 can generate a driving/sensingsignal S1, a storage control signal S2, and a decoding control signalS3. Wherein, the driving/sensing control signal S1, the storage controlsignal S2, and the decoding control signal S3 have a driving/sensingcontrol timing, a storage control timing, and a decoding control timingrespectively and used to control the driving/sensing module 30, thestorage control module 40, and the decoding control module 50respectively, but not limited to this.

It should be noticed that the plurality of pins 20 of the touch sensingapparatus 1 has more than one function, and the plurality of pins 20 canbe switched among different functions according to practical needs, suchas a driving function, a sensing function, a ground function, and afloating function, but not limited to these functions.

When the at least one driving/sensing module 30 receives thedriving/sensing control signal S1 from the logic control module 10, thedriving/sensing module 30 will control the plurality of pins 20 toperform the plurality of functions respectively according to thedriving/sensing control timing of the driving/sensing control signal S1,so that the plurality of pins 20 can sense a plurality of analog data(sensed voltages) from the ITO sensor 100 at the same time, and storethe plurality of analog data in storage capacitances of the at least onestorage control module 40.

As shown in FIG. 1, the ITO sensor 100 includes a plurality of sensinglines 80 and a plurality of driving lines 90, and the plurality ofsensing lines 80 and the plurality of driving lines 90 are vertical toeach other. It should be noticed that the sensing lines 80 and thedriving lines 90 are interchangeable. That is to say, 90 of FIG. 1 canalso be sensing lines, and 80 of FIG. 1 can also be driving lines, andthe interchange can be controlled by the touch sensing apparatus 1. Inthis embodiment, because different pins 20 can scan a driving line 90respectively, and sense the plurality of sensing lines 80 at the sametime, the plurality of pins 20 can sense the plurality of analog data(sensed voltages). In fact, the logic control module 10 of the touchsensing apparatus 1 can select a specific pin of the plurality of pins20 to control to sense at a specific timing.

It should be noticed that the logic control module 10 can generate thecontrol signals S1˜S3 having different control timings according to anexternal synchronous signal, or the logic control module 10 can alsogenerate the control signals S1˜S3 having different control timings onits own without the external synchronous signal, so that when the pins20 senses analog data, the time period of the noise generated by the LCDpanel can be avoided and the analog data sensed by the pins 20 will notbe affected by the noise.

It should be noticed that because the main technologic feature of theinvention is the storage control module 40 and the decoding controlmodule 50 of the touch sensing apparatus 1, the circuit structure andfunctions of the storage control module 40 and the decoding controlmodule 50 will be introduced in detail as follows.

Please refer to FIG. 2. FIG. 2 shows a circuit schematic figure ofsingle storage control module 40 and single decoding control module 50of the touch sensing apparatus 1. As shown in FIG. 2, each storagecontrol module 40 includes a plurality of storage capacitors C1˜C3 andswitches SW1˜SW3 corresponding to the storage capacitors C1˜C3. Itshould be noticed that the number of storage capacitors and thecorresponding switches of each storage control module 40 is not limitedto three, and each storage control module 40 can also include multiplesets of storage capacitors and corresponding switches.

The switches SW1˜SW3 are coupled between the storage capacitors C1˜C3and the driving/sensing module 30 respectively. When the storage controlmodule 40 receives the storage control signal S2 from the logic controlmodule 10, the storage control module 40 will receive the analog data(sensed voltages) sensed by pins 20 from the driving/sensing module 30and store each analog data in different storage capacitors C1˜C3 atdifferent times respectively according to the storage control timing ofthe storage control signal S2.

In fact, the storage control module 40 controls whether each analog datais stored in the storage capacitors C1˜C3 by switching on or off theswitches SW1˜SW3. For example, if the switches SW1˜SW3 is under ONstate, at a first time, the storage control module 40 switches off theswitch SW1 and keeps the switches SW2 and SW3 under ON state, a firstanalog data outputted from the driving/sensing module 30 can be storedin the storage capacitor C1; at a second time, the storage controlmodule 40 switches off the switch SW2 and keeps the switches SW1 and SW3under ON state, a second analog data outputted from the driving/sensingmodule 30 can be stored in the storage capacitor C2; at a third time,the storage control module 40 switches off the switch SW3 and keeps theswitches SW1 and SW2 under ON state, a third analog data outputted fromthe driving/sensing module 30 can be stored in the storage capacitor C3.Therefore, the storage control module 40 can store each analog dataoutputted from the driving/sensing module 30 in different storagecapacitors C1˜C3 at different times respectively. It should be noticedthat the order and method of the storage control module 40 controllingthe switches SW1˜SW3 on or off are not limited by the above-mentionedcases, the switches SW1˜SW3 can be switched off at the same time orswitched on different times to enhance the scanning rate and report rateof the apparatus, so that it can be adjusted based on practical needs.

After the storage control module 40 store all analog data outputted fromthe driving/sensing module 30 in the storage capacitors C1˜C3, theswitches SW1˜SW3 can be switched on and the ITO sensor 100 will becontrolled to perform a discharge process to avoid the environmentalnoise affecting the operation of the control chip and avoid the residualcharges on the ITO sensor 100 affecting the sensing accuracy of the pins20.

It should be noticed that the touch sensing apparatus 1 of the inventionincludes at least one storage control module 40 and the operation ofeach storage control module 40 is the same. The logic control module 10generates the storage control signal S2, so that the storage controlmodule 40 can store the analog data in the storage capacitorsrespectively.

Next, single decoding control module 50 will be introduced. As shown inFIG. 2, the decoding control module 50 includes switches SW4˜SW8 and abuffer A1. Wherein, the switches SW4˜SW6 are coupled between the storagecapacitors C1˜C3 and the buffer A1 respectively; the switch SW7 is adischarging switch coupled between the switches SW4˜SW6 and the bufferA1; the switch SW8 is coupled between the buffer A1 and the amplifyingmodule 60.

In this embodiment, the switches SW4˜SW6 and the switch SW7 are allunder ON state, the decoding control module 50 can have two differentoperation modes:

In the first operation mode, the decoding control module 50 decodes thesensed voltages stored in different storage capacitors C1˜C3 atdifferent times respectively according to the decoding control timing tooutput decoded analog data to the amplifying module 60. For example, atthe first time, the decoding control module 50 switches off the switchSW4 and keeps the switches SW5 and SW6 under ON state according to thedecoding control timing, therefore, the first analog data stored in thestorage capacitor C1 can be transmitted to the buffer A1. If the switchSW8 is under OFF state, the buffer A1 can output the decoded firstanalog data to the amplifying module 60. At the second time, thedecoding control module 50 switches off the switch SW5 and keeps theswitches SW4 and SW6 under ON state according to the decoding controltiming, therefore, the second analog data stored in the storagecapacitor C2 can be transmitted to the buffer A1. If the switch SW8 isunder OFF state, the buffer A1 can output the decoded second analog datato the amplifying module 60. At the third time, the decoding controlmodule 50 switches off the switch SW6 and keeps the switches SW4 and SW5under ON state according to the decoding control timing, therefore, thethird analog data stored in the storage capacitor C3 can be transmittedto the buffer A1. If the switch SW8 is under OFF state, the buffer A1can output the decoded third analog data to the amplifying module 60.

In the second operation mode, the decoding control module 50 performsanalog filtering and decodes the sensed voltages stored in differentstorage capacitors C1˜C3 at the same time according to the decodingcontrol timing to output the decoded analog data to the amplifyingmodule 60. In fact, the decoding control module 50 performs analogfiltering to the sensed voltages stored in different storage capacitorsC1˜C3 in a charge sharing method, but not limited to this case.

For example, at certain specific time, the decoding control module 50switches off the switches SW4˜SW6 at the same time according to thedecoding control timing. Because the switch SW7 is kept under ON state,the first sensed voltage, the second sensed voltage, and the thirdsensed voltage respectively stored in the storage capacitors C1˜C3 canbe all transmitted to the buffet A1. At this time, the charge sharingwill be generated in the decoding control module 50, just like the firstsensed voltage, the second sensed voltage, and the third sensed voltageare averaged, so that the analog filtering effect can be achieved. Ifthe switch SW8 is under OFF state, the buffer A1 can output the decodedthird analog data to the amplifying module 60.

It should be noticed that after the first sensed voltage, the secondsensed voltage, and the third sensed voltage respectively stored in thestorage capacitors C1˜C3 are outputted to the buffer A1, the sensedvoltages are amplified by the amplifying module 60 and then theamplified sensed voltages are converted into digital data S4 by theanalog/digital converting module 70, and then the decoding controlmodule 50 switches off the switches SW4˜SW6 and the discharging switchSW7, and the storage capacitors C1˜C3 is performed a discharging processto reduce the residual charges in the storage capacitors C1˜C3.

Then, the amplifying module 60 is used for amplifying the analog data(the first sensed voltage, the second sensed voltage, and the thirdsensed voltage) decoded by the decoding control module 50; theanalog/digital converting module 70 is used for converting the amplifiedsensed voltages into the digital data S4. In fact, the amplifying module60 can be differential amplifier or other types of amplifier, and theanalog/digital converting module 70 can be any types of analog/digitalconverter without any limitations.

Then, the analog/digital converting module 70 will output the converteddigital data S4 to the logic control module 10. In fact, the logiccontrol module 10 can include digital filter (not shown in figures) usedfor performing digital filtering to the digital data S4 to reduce theinterference of noise. It should be noticed that because the decodingcontrol module 50 already uses the charge sharing to realize the analogfiltering function to reduce the error of analog data, so that when theanalog data is amplified and converted into digital data, the accuracyof digital data can be largely increased, so that the loading of thelogic control module 10 of digital end can be reduced to achieve theeffect of enhancing the touch accuracy of the touch sensing apparatus 1.

Compared to the prior arts, the touch sensing apparatus of the inventionuses the charge sharing concept to realize the function of analogfilter, not only the interference to touch sensing caused by the noisegenerated by the liquid crystal panel and external environment can beeffectively reduced, but also the reporting rate of the entire systemwill be not reduced and the power consumption will be increased,therefore, the touch sensing apparatus can sense the touch points on thetouch panel more accurately to largely reduce the probability ofmisjudgment.

With the example and explanations above, the features and spirits of theinvention will be hopefully well described. Those skilled in the artwill readily observe that numerous modifications and alterations of thedevice may be made while retaining the teaching of the invention.Accordingly, the above disclosure should be construed as limited only bythe metes and bounds of the appended claims.

What is claimed is:
 1. A touch sensing apparatus, comprising: a logiccontrol module, for generating a plurality of control signals havingdifferent control timings, and the plurality of control signalscomprising a storage control signal and a decoding control signal; atleast one storage control module, coupled to the logic control module,each storage control module comprising a plurality of storage capacitorsand respectively storing each of sensed voltages in different storagecapacitors at different times according to a storage control timing ofthe storage control signal, wherein the sensed voltages are analog datasensed from scan lines of an ITO sensor; and at least one decodingcontrol module, coupled to the logic control module and the at least onestorage control module, for decoding the sensed voltages stored in thestorage capacitors according to a decoding control timing of thedecoding control signal to output the decoded analog data; wherein eachdecoding control module performs an analog filtering process to anddecodes the sensed voltages stored in different storage capacitors atthe same time to output the decoded analog data.
 2. The touch sensingapparatus of claim 1, wherein the each decoding control module performsthe analog filtering process to the sensed voltages stored in differentstorage capacitors in a charge-sharing way.
 3. The touch sensingapparatus of claim 1, wherein after the at least one decoding controlmodule decodes all of the sensed voltages stored in the storagecapacitors, the storage control module performs a discharge process tothe storage capacitors.
 4. The touch sensing apparatus of claim 1,further comprising: a plurality of pins; and at least onedriving/sensing control module, coupled to the logic control module andthe plurality of pins, for receiving a driving/sensing control signal ofthe plurality of control signals from the logic control module andcontrolling the plurality of pins to perform a plurality of pinfunctions respectively according to a driving/sensing control timing ofthe driving/sensing control signal, so that the plurality of pins cansense the sensed voltages from the scan lines of the ITO sensor.
 5. Thetouch sensing apparatus of claim 4, wherein the plurality of pinfunctions comprises a driving function, a sensing function, a groundfunction, and a floating function.
 6. The touch sensing apparatus ofclaim 1, further comprising: an amplifying module, coupled to the atleast one decoding control module, for amplifying the decoded analogdata; and an analog/digital converting module, coupled to the amplifyingmodule and the logic control module, for converting the amplified analogdata into a digital data and transmitting the digital data to the logiccontrol module.
 7. The touch sensing apparatus of claim 6, wherein thelogic control module comprises a digital filter used for performing adigital filtering process to the digital data to reduce noiseinterference.
 8. The touch sensing apparatus of claim 1, wherein thelogic control module generates the plurality of control signals havingdifferent control timings according to an external synchronizing signal.